Geology is all around us, scarcely thought of as we go about our lives. Yet, it affects everything we do as a civilization, as a society and as individuals. While barely appearing to change from day to day, it works to alter the course of evolution. Preserving a record of creatures and landscapes both ancient and forgotten, the story of our past is written in stone and waiting to be read. I offer a view of how I see our world and its inhabitants, both past and present, as seen through my lens.

Sunday, June 29, 2014

Geological Legacies of the Paris Basin: Part II – Subterranean Limestone Quarries and Catacombs of Paris

"...Paris has another Paris under herself…which has its streets, its intersections, its squares, its dead ends, its arteries, and its circulation”Les Miserables, Victor Hugo, 1862

For a discussion of the tectonic evolution of the Paris Basin, its Lutetian stratigraphy and the gypsum deposits of the Right Bank, please visit my previous post entitled "Geological Legacies of the Paris Basin: Part I - Plaster of Paris, the Windmills of Montmartre, the Park of Buttes-Chaumont and a New Artistic Creativity" here.PARIS SOUTERRAIN - PARIS UNDERGROUNDStroll the narrow cobbled streets and broad boulevards on the Left Bank of the old French capital. Enjoy Paris’s beautiful storefronts, its exquisite monuments, museums, parks and stunning architecture. Languish in a sidewalk café or dine in a fashionably chic bistro. For the casual observer, it’s impossible to imagine what lies underfoot – 20 to 25 meters below street level. Paris is a city of layers – both above ground and below. Its underground has many new additions, while others are vestiges of the past, often lost and forgotten. Some are accessible to the public, and others have been sealed for an eternity.

There are Roman Empire foundations and more recent wartime shelters, medieval basements and mysterious church crypts, musty wine cellars and shadowy mushroom farms, subterranean shopping malls and modern multi-level car parks. Factor in 1,305 miles of storm drains and sewers, 133 miles of Métro and RER railway tunnels, and countless miles of utility lines and pipes for water, gas, electricity and telephone. Standing on the streets of Paris, you'd never suspect what exists below you unless you looked at a map of the underground that mirrors the landscape above.

Modified from the Atlas du Paris Souterrain – a highly-recommended source of information!

Yet, there exists an even deeper layer! On the Right Bank, the buttes of Montmartre and Belleville are riddled with gypsum quarries. On the Left, Paris is honeycombed with a labyrinth of over 200 miles of cavernous limestone quarries replete with a macabre section known as the Catacombs – after the ones in Rome.

The Catacombs is a dimly lit, musty maze of galleries and corridors lined with the bones of 6,000,000 (seven by some counts) disinterred Parisians. In one section, a water-filled well contains the stratigraphic contact of the Lutetian age 45 million years ago. How did these two “cities” evolve? How do they co-exist? A luminous City of Light above another of shadows and darkness.

GEOLOGIE PIEDS DE PARIS - PARIS’S GEOLOGY UNDERFOOTThe city of Paris occupies a tiny portion of the extensive Paris Basin – a 140,000 square kilometer shallow epicontinental trough of flat valleys and low plateaus in the north of France. On a larger scale, the depocenter of the Anglo-Paris Basin that spans the English Channel into Great Britain resides on the continental shelf of the Eurasian plate. Its foundation is a Late Proterozoic Cadomian-late Paleozoic Variscan crystalline basement. Please visit my post Part I for the Paris Basin’s juicy tectonic details here.

Paris (red dot) within the extensive Anglo-Paris Basin on a Jurassic through Neogene Surficial Geology Map

During the late Paleozoic, the basin began to form subsequent to extensive orogenic collisions that formed Pangaea in the western hemisphere. By the end of the Mesozoic, the basin (along with the assemblage of France, Belgium, Great Britain, Scandinavia and Western Europe) was tectonically transported to the eastern hemisphere on the Eurasian plate when Pangaea fragmented apart and the Atlantic Ocean opened its waters. The basin’s strata were deposited in a multitude of Tertiary age transgressions and regressions of tropical seas that flooded the epicontinent of Western Europe. Formed in a mixed environment of marine, coastal, lagoonal and freshwater conditions, deposition was followed by compaction, cementation and eventual lithification.

Modified from Ron Blakey and Colorado Plateau Geosystems, Inc.

The sedimentary rocks that formed - during the Eocene epoch in particular - built the city of Paris: Bartonian age gypsums (gypse) for plaster of Paris on the Right Bank (north side of the river Seine) and Lutetian age limestones (calcaire grossier), chalks (craie) for lime-based cements and paints, clays (argile) for tiles and bricks, and sand (sable) for masonry on the Left Bank (south of the river). The deposits on each side of the river Seine are between two low plateaus, Montmartre and Montparnasse. Both banks were exploited from under the city, as Paris grew and expanded on the surface.

ANTICLINE OF MEUDONFortuitously for Paris’s architectural future, the axis of the Tertiary age anticline of Meudon (red dotted line below) passes south of the city. The flexure allowed for the excavation of Paris’s geological bounty of gypsum from the Right Bank and deeper, coarse limestone from the Left.

Modified from M. Vire of MNHM and Jean-Pierre Gely, 2013

The geologic transect (black line above) extends across the basin from north to south and is represented cross-sectionally below. Note the availability of Lutetian limestone (calcaire grossier) south of the Seine on the Left Bank and gypsum (gypse) north of the Seine on the Right Bank in Montmartre. The vertical scale across the basin is greatly exaggerated making Montmartre appear like the Matterhorn.

Modified from M. Vire of MNHM and Jean-Pierre Gely, 2013

TWO MAJOR EXPLOITATION ZONES OF PARISThus, gypsum has been extracted in the hills of Paris on the Right Bank from Menilmontant, Montmartre and Buttes-Chaumont areas of the 18th, 19th and 20th arrondisements, respectively. Limestone was mined under the small Parisian hills of Montparnasse, Montsouris, Montrouge, the Butte aux Cailles and the Colline de Chaillot, largely on the Left Bank.

Topographical Considerations of ParisModified from Arch.ttu.edu

ANCIENNES CARRIÈRES DE PARIS - ANCIENT MINES OF PARISThe areas of Right Bank gypsum (green clusters) and largely Left Bank limestone (red) exploitation can be seen highlighted on this old Paris map of 1908. The direction of flow of the River Seine is shown in black arrows.

Wikipedia

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THE ROMAN CITY OF LUTETIABy 53-52 BC, the Romans had conquered Gaul (roughly France and Belgium) and the Celtic Iron Age tribes living in the region. Within the Paris Basin, that included the Parisii, living on the banks of the river Seine. The Romans called their settlement on the hills south of the river Lutetia Parisiorum or Lutece in French. The name was derived from a Parisii word meaning marsh or swamp. In turn, geologists borrowed the name for the Lutetian age - a division of the Eocene epoch of the Cenozoic Era- the time in which the limestone called “Paris Stone” formed – 47.8 to 41.3 million years ago.

The decision to settle above the banks of the Seine was governed by its ideal location for trade, defense and availability of raw materials especially water and the limestone for Roman buildings, military fortifications and roads. The Roman and Medieval era that followed produced lasting design elements for the development of the city from the Renaissance through the 21st century.

Please note the Roman open quarries (right) in the vicinity of the River Bievre near its confluence with the Seine (lower right), and the Arenes de Lutece amphitheater. As a modern reference, the island in the middle of the Seine in the upper right corner is Île de la Cité that houses the Cathedral of Notre Dame.

A DOZEN CENTURIES OF LIMESTONE EXPLOITATIONThe Romans in the 1st century and the early Parisians through the end of the 12th century acquired coarse limestone for structures in the most instinctive of ways – from above ground where it was most convenient. It was removed from open quarries (carrières à ciel ouvert) where it had been exposed by erosion such as the region of the Seine’s ancestral tributary, the Bievre (see above). The technique was primitive, but the rock was readily available and had existing natural fractures that facilitated its extraction.

One such quarry, virtually unrecognizable today, lies within the heart of Paris beneath the Arena of Lutece, a partially restored Roman amphitheater. Once considerably larger, the majority of the arena’s limestone has been repurposed into structures subsequently built throughout the millennium.

MINING GOES UNDERGROUNDBy the end of the 12th century, medieval Paris had become a medium-size, walled city with a population of 25,000 surrounded by countryside of farms and vineyards. The extraction of surface limestone was gradually replaced by underground workings to satisfy the sharply increased needs for building construction such as Notre-Dame Cathedral, the Louvre Palace and the ramparts of the city.

Mining below the surface also minimized the excavation of overburden, allowed deeper fine-grained deposits to be reached and conserved topsoil for farming immediately around the growing city. The first underground excavations were essentially extensions of the open quarries by digging horizontally into a hillside exposure (left diagram).

Modified from M. Vire of MNHM and Jean-Pierre Gely, 2013

PILIERS TOURNESThe first mining method employed the “room and pillar” technique, called piliers tournes. After a horizontal tunnel was excavated, perpendicular and then parallel tunnels were added (right diagram). The result was a maze of interconnecting passageways with the weight of the ceiling supported by a grid of massive columns of untouched, solid limestone. It helped to prevent collapse of the undermined roof, but a significant portion of usable excavated material was lost.

In the 15th century, vertical wells were sunk and then tunnels were dug horizontally from there. In order to raise limestone blocks to the surface, wheeled wooden winches reminiscent of “squirrel” wheels were driven by workers climbing rungs, oxen or horses to raise blocks of limestone vertically. The system could haul up large slabs that weighed as far as 30 meters down.

Modified from M. Vire of MNHM and Jean-Pierre Gely, 2013

These mining techniques were also used on gypsum deposits for plaster of Paris in Montmartre and the Belleville hills on Paris’s Right Bank. Although artificially engineered, the grotto at the Park of the Buttes-Chaumont is reminiscent of the cathedral-like excavation structures that undermine the region. Please visit my previous post regarding gypsum excavation on the Right Bank here.﻿

HAGUES ET BOURRAGES AND PILIERS A BRASIn the 16th century, the mining method of hagues et bourrages was employed that was economically productive and structurally sound. Instead of tunneling horizontally into the exploited table of limestone, miners would extract stone progressively outward from a central point. When the ceiling became sufficiently unsupported, a line of stacked piliers a bras was erected from the floor to the ceiling. When extraction continued outward, a second line of stone columns was added, which were then transformed into walls or hagues as the space in between was backfilled with waste rubble or bourrage.

For a fantastic and imaginative 3-D tour of the evolution of Paris beginning with the early Celtic settlement, check out the video here. A fine appreciation will be gained for the volume of limestone that was extracted beneath the Left Bank during the building of the city.

SUBSIDENCE SINKHOLES ON MINED-LANDThe first underground limestone quarries were located in Paris's suburbs (faubourgs) on the Left Bank. As the city continued to grow, new underground quarries with interconnecting galleries were developed on the city’s expanding periphery. Old abandoned quarries fell into oblivion and were gradually built over.

Although the undermined state of the Left Bank was known to city architects in the early 17th century, Parisian’s became painfully aware of their precarious existence over the subterranean voids when they began to cave in. At first many thought it to be the work of the devil. Called subsidence sinkholes (fontis in French), the cave-ins varied in size with some affecting houses and others affecting entire streets.

Formation and Evolution of Subsidence A fontis is a cavity that develops when the roof of a subterranean gallery caves in.A cloche is the rounded top of the rubble pile.Modified from Daniel Munier and from M. Vire

The arched void forms that migrates upward as the ceiling rocks gradually tumble in. When the sinkhole finally breaks through the surface, the rounded top of the rubble pile or cloche can be viewed within the sinkhole from above - giving the cavity that has formed a bell shape. These sinkholes should not be confused with those that occur in a karstic landscape, which develops under a cover of soluble rocks - also limestone - via acidic water that has acquired atmospheric carbon dioxide.

CATASTROPHE IN THE MOUTH OF HELLWhen the largest collapse occurred in 1774, a wave of panic spread through Paris. A giant sinkhole catastrophically swallowed a busy Parisian neighborhood including roads, buildings, houses, horses, carriages, oxcarts and throngs of people along Rue d’Enfer (now called Boulevard Saint Michel near Avenue Denfert-Rochereau). Appropriately, enfer is the French word for “hell,” and the gaping hole in the earth became known as the “mouth of hell.” The quarries that built the city of Paris were literally threatening to destroy it - neighborhood by neighborhood.

How ironic! The limestone that went into the construction of Notre-Dame, the Palais-Royal and the mansions of the Marais on the surface of Paris actually had come from the quarries beneath Rue d’Enfer – now taking revenge upon the city.

Explographies.com

“Paris (had) begun to devour its own foundations – sand for glass and smelting, gypsum for plaster, limestone for walls, green clay for bricks and tiles.”

From Graham Robb’s “Parisians: An Adventure History of Paris”

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THE MAN WHO SAVED PARIS FROM SINKINGIn response to the fear of collapse, King Louis XVI designated a commission to investigate the state of the Parisian underground on April 4, 1777. It was called the Inspection Unit for Quarries Below Paris and Surrounding Plains. The head of the newly minted office - appointed by the King by chance of fate only a few hours before the collapse - was an architect named Charles-Axel Guillaumot, who held the position of General Inspectorate of the Quarries (IGC) until his death in 1807 - in French, Inspection Générale des Carrières.

“Guillaumot inspected the "gaping wound as an explorer

could contemplate the shores of a new continent.” Author Graham Robb

This “Savior of Paris" that the city owes so much set about to inspect and map the fragile voids under the entire city, many of which were illegal and uncharted but most abandoned and forgotten. His goal was to excavate them where needed and reinforce (consolidate) them from future collapse. Virtually every chamber was mapped and assigned a name that corresponded to the street above. The inspected walls still bear his chiseled signature, a "G" and date.

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Following in the tradition of Guillaumot, engineers from the Inspection des Carrieres generally signed and dated their consolidation projects by carving their initials, order number and the years the work was carried out into the walls. Fleur-de-lis, the royal symbol of the French Empire, were obliterated from most of the signatures during the French Revolution.

A DOUBLED PARISIn order to safeguard public roads and of course the King’s properties, Guillaumot erected pillars from the quarry floors to their ceilings, “retrospectively-created foundations for the edifices built on the surface” (Gilles Thomas). The result was that every undercut surface street was doubled by a gallery that followed the same layout. In a sense, Paris became a mirrored city with one above ground and the other below. This allowed the evolution of subsidence voids to be monitored and shored up as needed. The same can be said of the modern city of Paris with its underground double. Here's an example from the 13th arrondissemont.

From DecodingParis.com

In Guillaumot’s own words:

“To monitor the preservation of these constructions at all times,It was necessary to render them accessible; to this effect,a gallery wide enough to allow passage of construction materials was left under and within the public way; at the gallery’s farthest point, another wall was built.Perpendicular galleries were dug here and there to enable communication betweenboth sides of the public way and to allow movement from one gallery to the next.”(Memoirs on the Work Ordered in Quarries in Paris and Adjacent Plains, 1804)

LES CIMETIÈRE DES SAINTS-INNOCENTS - THE SAINTS-INNOCENTS CEMETERYAnother peril was threatening the city – an insidious one that had become equally intolerable and every bit as dangerous. Paris’s cemeteries had become horrifically overcrowded. The earliest burial grounds were on the southern out-skirts of the Roman-era city on the Left Bank - outside the city! By the 4th century, burials had moved to the Right Bank on filled-in marshland - within the city. In particular was the property of the Saints Innocents church in 1130 - named after the biblical narrative of the "Massacre of the Innocents" by Herod the Great, the Roman-appointed King of the Jews.

No larger than a city block and literally within a few blocks of Notre-Dame in the midst of Paris’s densely inhabited area in the current district of Les Halles, problems began to pile up, literally. The foundation of Paris’s first Christian churches were somewhat removed from the center of population and many became crypts for those seeking a final resting place closer to god, a service only available to the wealthy. Common folk were buried outdoors on consecrated clergy property, close to their creator in the "fresh" air. One would think!

Map of Paris in 1550The Cemetery of Saint-Innocents is circled for reference. Click for a larger view.Modified from OldMapsofParis.com in the Public Domain

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Saint-Innocents had become Paris’s principal cemetery, although there were countless burial grounds in the city. Saint-Innocents was adjacent to the city’s principal marketplace Les Halles, where fresh farm products were sold daily. Burying the dead in town was a radical departure from the norm, contrary to logic, sound urban planning and public health.

The red ellipse encompasses the Cemetery of Saint-Innocents that included the central burying ground, the church and the surrounded charnel house. Notice the proximity of Saint-Innocents to the central market Les Halles - now known as Forum des Halles. This ambitious, aerial urban map of 1739 before the city’s redesign by Baron Georges Eugene Haussmann is but a small section of Paris with accurate detail of every building drawn down to the windows. You can visit the entire city map here.

Turgot-Berez Map Plan of Paris in 1739Modified from geographicus.com/blog/rare-and-antique-maps/antique-map-of-the-week-the-turgot-bretez-plan-of-paris

By the end of the 19th century, the burial ground in Saints-Innocents has become a two and one half meter-high mound filled with over ten centuries of dead bodies largely from Paris’s 22 parishes – perhaps two million. The corpses had accumulated from natural causes, disease (particularly cholera and plague), famine, wars, and the collected remains from hospitals such as the Hôtel-Dieu and the morgue. Other Parisian parishes had their own burial grounds, but the conditions in Saints-Innocents were by far the worst.

LES CHARNIERS - THE CHARNEL HOUSE

In an attempt to relieve the overcrowding, Saints-Innocents was enlarged and surrounded by a high wall. What had begun as a cemetery of individual sepulchers - burial chambers such as crypts and tombs - had become a site for mass graves with large numbers of bodies buried in a single pit. When a mass grave was filled, a new one was initiated. And so on.

To make room for more burials in the 14th and 15th centuries, charniers or charnel houses (from a Latin derivative relating to flesh) were constructed around the burying ground to act as a repository for the overflow of corpses from the burying ground.

Wikipedia

The long dead were exhumed and their bones were tightly packed into the walls and roofs of the charnier galleries. Bones were stacked in an almost artfully decorative pattern, while outside, rotting corpses on the grounds poisoned the air with a nauseating stench. Those living in proximity to the cemetery and certainly those downwind were the first to suffer. Broth and milk were said to sour within hours. The tapestries of merchants in nearby Les Halles discolored quickly. Wine turned to vinegar and resting one’s hand on damp, moldy walls was a risky endeavor. In nearby churches, the generous use of incense was insufficient to mask the foul stink. The French writer Louis-Sébastien Mercier (1740-1814) wrote:

“The stench of cadavers could be smelt in almost all churches;

…the reek of putrefaction continued to poison the faithful.

Rats live among the human bones, disturbing and lifting them,

seeming to animate the dead as they indicate to the present generation

they among which they will soon stand...

They (the bones) will soon all turn to chalky earth.”

A close up of the charnel house shows the skulls stacked in the upper tiers, while rotting corpses literally littered the burying grounds. Now lost but recorded in manuscripts, a mural of Danse Macabre or the Dance of Death was painted on the south wall within an alcove of the charnel house. Represented in many languages and countries, the theme dates from 1424-24. No matter one’s station in life, the universality of death depicted in the “dance” is an artistic genre of late-medieval allegory. It was meant to remind people of life’s fragility and the vainness of the glories of their earthly lives. One might think that a view of the burial grounds was likely all that was needed!

Wikipedia

Further insight into the unhealthy conditions at Saint-Innocents can be gleaned from Mercier’s description of the insalubrious state of affairs at the hospital Hôtel-Dieu on nearby Île de la Cité:

“Hôtel-Dieu has all it takes to be pestilential (contagious), because of its damp and unventilated atmosphere; wounds turn gangrenous more easily, and both scurvy and scabies wreak havoc when patients sojourn there. What in theory are the most innocuous diseases rapidly acquire serious complications by way of the contaminated air;for that precise reason, simple head and leg wounds become lethal in that hospital.Nothing proves my point so well as the tally of patients who perish miserably each yearin the Paris Hôtel-Dieu…a fifth of the patients succumb; a frightful tally treated only with the greatest indifference.”

LOUIS XVI ISSUES EDICTSNothing was done to remedy the intolerable situation until King Louis XV initiated an investigation in 1763. His successor, King Louis XVI, in his first year on the throne in 1775, issued an edict to move the deceased out of the city. The church resisted the notion, which profited from burial fees. Business was good! To reduce the number of burials, the price was increased, something only the wealthy could afford.

Wikipedia

In 1780, a mass grave containing over 2,000 partially-decomposed bodies collapsed under the sheer weight spilling into an adjacent basement on Rue de la Lingerie. The event further heightened concerns for public health and hastened the decision to eliminate Saint-Innocents once and for all. That same year the edict was issued that forbade burying corpses at Saint-Innocents and all other cemeteries within the city limits of Paris.

At a time when Saints-Innocents housed over two million corpses, one major problem had been solved, but a greater one was created. What to do with the overflowing contents of Saint-Innocents?

MINE RENOVATIONS AND CEMETERY CLOSURES OFFER A COMMON SOLUTIONMine consolidations were still under way and included the addition of a network of interconnecting subterranean passageways for access. With the cemeteries closed, Police Prefect Lieutenant-General Alexandre Lenoir supported an idea of moving the dead to the newly renovated corridors to be used as an underground sepulcher. The idea became law in 1785. Saints-Innocents was to be evacuated and converted into the public square that has remained to this day, Place Joachim-du-Bellay – more on that story later in this post.

The location for the collective burial ground was a spot designated in popular culture as the Tombe-Issoire within the limestone quarries of the Montrouge Plain outside Paris - more precisely, the suburb of Petit-Montrouge. The region is on the hillsides on the left bank of the Bièvre River mentioned earlier and riddled with limestone quarries at depth. At the time, the commune was outside the city walls of the Wall of the Farmers-General, used primarily for tax collection rather than defensive purposes. It was variously known for its monasteries, religious orders, royal hunting grounds, windmills and, of course, its quarries. Today, there are no famous monuments in the suburb of Montrouge. The major tourist attraction is beneath the quarter!

The location of the Plains of Montrouge outside the walls of the city of Paris

THE CATACOMBS BECOME AN OSSUARYOn April 7, 1786, the grounds of the former quarries of the Tombe-Issoire under the Plain of Montrouge (the burial site of a legendary giant named Issoire slain by William the monk) were sanctified in the presence of the church abbots, the architects of the project and Charles-Axel Guillaumot. On November 16th, Monseigneur Leclerc de Juigne and Archbishop of Paris ordered:

“the removal of the Saints-Innocents Cemetery, its demolition and its evacuation,entailing the turning of the soil to a depth of five feet and the sieving of earth,with any remaining corpses or bones to be transported and buriedin the new underground cemetery of the Montrouge Plain.”Cited in Les Catacombes, etude historique, 1861

The Tomb was called the Catacombs of Paris, in French, Les Catacombes de Paris, after the Roman Catacombs. Although Paris’s early limestone quarries date back to the Roman period, the Catacombs do not. And, unlike the Roman Catacombs, they were never excavated for the purposes of burial, only repurposed for burial after the space had been established. The official name for the catacombs is L’Ossuaire Municipal or The Municipal Ossuary.

THE EXHUMATION AND TRANSFER OF BONESThe first transfers of bones from Saints-Innocents to the Catacombs lasted 15 months and continued with the populations of Saint-Étienne-des-Grès, Saint-Eustache, Saint-Landry, Sainte-Croix-de-la-Bretonneries, Saint-Julien-des-Ménétriers and so forth. Continuing to 1814, every cemetery, church ground, crypt and tomb of Paris was nocturnally emptied of its human remains. In total, over six million Parisians were withdrawn and transported to their new “haven of peace” beneath the Plains of Montrouge. The exact number is impossible to determine. The estimate is based on the number of burials up to the year 1860 when the contents of the last graves were transferred to the ossuary.

The enormous transportation of bones was scrupulously ritualized and conducted at nightfall. Torchbearers followed by priests wearing surplices and stoles accompanied funerary carts draped in black sheets while chanting the Mass of the Dead. The poet Gabriel Marie Jean Baptiste Legouvé (1804) described the procession as a “shapeless debris-monument to the departed.”

Wikipedia

LES CATACOMBES DE PARIS - THE CATACOMBS OF PARISThe Catacombs of Paris lie some 20 meters beneath the south Paris suburb of Montrouge. The town bears little resemblance to the former bucolic royal hunting ground on the Plain of Montrouge. In fact, one must look hard to identify buildings of “old” pre-Haussmann Paris, but they’re there. In fact, you arrive beneath one if you take the Paris Métro at Denfert-Rochereau station, and you must enter one in order to descend into the Catacombs!

A good landmark on the street is the bronze statue called the Lion of Belfort within the square, now auto-roundabout. Theatergoers may recognize it as the backdrop at the beginning of the third act of La Bohème by Puccini. General Pierre Philippe Denfert-Rochereau (nicknamed the Lion) achieved fame by courageously fighting against the invading Prussians in 1870 at the city of Belfort in northeast France. Anxious to put a positive spin on his defeat and looking for heroes of the conflict to glorify, French authorities erected the majestic statue in the center of Place Denfert-Rochereau. By the way, the statue was created by Auguste Bartholdi, the father of the Statue of Liberty.

Place Denfert-Rochereau was previously known as Place d’Enfer or the “Place of Hell”, the street of the infamous collapse of 1774. Rue Denfert-Rochereau was formerly called Rue d'Enfer or the “Street of Hell.” “Denfert” and “d’Enfer” are pronounced exactly the same, a coincidence too perfect for the Paris city hall to ignore when they changed the name - an apparent municipal pun. Interesting sense of humor those French.

Here the square and the lion on a 1932 map of Paris. Notice the green space immediately to the west of the Place Denfert-Rochereau. It's the Montparnasse Cemetery. After all cemeteries had been banned in Paris for health concerns, several new cemeteries outside the precincts of the capital replaced all the internal Parisian ones in the early 19th century: Montmartre Cemetery in the north, Père Lachaise Cemetery in the east and Montparnasse Cemetery in the south.

View of Barriere d'Enfer along the Wall of the Farmers-General. Note the nearby location of the Lion of Belfort and to the west, the Cemetery of Montparnesse.Modified from OldMapsofParis.com.

LA BARRIÈRE D’ENFER – THE GATE OF HELLImmediately south of the square is the Barrière d’Enfer – the gate built along the Wall of the Farmers-General around the city. Fermiers-Généraux or tax farmers collected octroi at the tollhouses, an unpopular (and highly abused) tax on goods both entering and leaving the city. The two tollhouses on the long-gone wall still remain - four of 62 surviving ones that punctuated the wall built between 1784 and 1791. Actually several walls surrounded Paris between the early Middle Ages to the mid-19th century, the others being for defense rather than tax collection.

For those interested, you can actually see the outline of the ancient wall on a Metro map of Paris by tracing metro lines 2 and 6, while wide boulevards replace the former fortifications. Also, the Rotunda at Parc Monceau on the north side of Paris on the Right Bank – originally called Barrière de Chartres - is an elegant tollhouse of the few that remain on the barrier wall.

Back at Denfert-Rochereau, two neo-classical tollhouses on the long-gone wall still remain. The easternmost building (right in the photo) is reserved for the Inspector General of the Quarries and is the site of entry into the catacombs – our entry into hell. The westernmost building (on the left) houses offices of the Directorate of Roads and Transport. Notice the Lion of Belfort on a pedestal in the center of the public square.

In spite of the nightly rituals of interment, the Catacombs were unknown to the public at large until 1810 when the second General Quarry Inspector, Louis-Étienne François Héricart-Ferrand, issued the first brochure that advertised their presence and began drawing curious Parisians into their depths. Prestigious figures that followed included Francis I of Austria in 1814 and Napoleon III and son in 1860. Today, the Catacombs have become a major tourist attraction and is managed by the City of Paris Cultural Affairs Division in association with the Carnavalet History of Paris Museum.

During the 1830’s to 1840’s, excursions were not limited to just the Ossuary and led by mine overseers “who guided them as struck their fancy; inevitable abuses occurred, the quarry galleries as well as the ossuary were damaged by unscrupulous people and visitor lost their way.” (Emile Gerards in Paris Souterrain, 1991).

OUR DESCENT INTO THE CATACOMBSWe arrived at the east pavilion of the Catacombs well before the opening time of 10 AM and found a line already forming at the entrance. Both Parisians and tourists alike want to be amongst the first 200 visitors allowed in, and we were no exception.

To enrich our experience, since tours are delivered in French, we arranged for an English-speaking guide and most affable fellow from Ireland (although audio-guides are available French, English and Spanish). He was extremely knowledgeable about both French and world history, and spoke four or five languages, so he was able to translate the 18th century signage in the Catacombs.

The entire tour covers a distance of about two kilometers and winds through a dimly lit labyrinth of galleries and interconnecting tunnels beneath the streets of Montrouge. The official brochure states that the average duration is 45 minutes, but we easily took twice that. There is a constant temperature of 14º C (57º F).

Be forewarned, as there are no toilet or cloakroom facilities within the Catacombs. Lastly, as stated by the official Catacombs Visitor's Guide, the tour is unsuitable for people with heart or respiratory problems, those individuals of a “nervous disposition” or claustrophobic, and young children. There is no disabled access to the Catacombs. The experience is quite macabre to those unaccustomed but incredibly fascinating in regards to Parisian history, geology and paleontology.

Between street level and the Catacombs, visitors travel back to the Lutetian age. At the bottom of the spiral staircase and before entering the Catacombs proper, visitors are guided to an exhibition entitled “The Sea in Paris – 45 Million Years Ago,” which ends December 31, 2014. The new installation “highlights a little known aspect of the Catacombs – their geological heritage, a real treasure-house in the subsoil of the capital.” (Of course you can read it all in my post Part I here).

A series of murals in both French and English takes you on the “journey through space and time” with paleographic maps, chronological profiles, photographs, drawings and engravings that beautifully demonstrate the evolution of the Paris Basin and the Lutetian Sea. In addition, there’s a detailed description of the Left Bank’s limestone quarries and the circumstances that led to their repurposing as an ossuary.

One of many geologic maps and cross-sections on display that depict the tectonic and geologic evolution of the Paris Basin and the region of Paris. My red arrows identify the underground limestone quarries (calcaire carriers souterraines de calcaire) of the Left Bank, south of the River Seine and the open air Roman quarries carrieres a ciel ouvert), also on the Left Bank, along the River Bievre.

After departing from the exhibition, the tour continues through a long interconnecting corridor. It seemed like a long distance to the Ossuary within the narrow walls and low ceilings.

Corridor leading to the Ossuary portion of the Catacombs

LES SCULPTURES DE PORT-MAHON - THE SCULPTURES OF PORT MAHON

The Catacombs is filled with many curiosities, not all of which are on display. Perhaps the most unique and popular is the sculpture created in 1782 by Beauséjour Décure, a discharged soldier who had been enrolled in the army of Richelieu during the re-conquest of Minorque. Although only a few details of his life are known, once discharged he worked in the quarries. During breaks, for five years Décure chiseled a replica of Port-Mahon, the principal port of Minorque, out of limestone. Wanting to make his creation more accessible, he was killed by a cave-in while opening an access stairway to his model. Currently, the sculpture is not included in the protective measures of the Ossuary and is threatened by a real estate project overhead. "C'est la vie."

LE BAIN DE PIEDS DES CARRIERS - THE QUARRYMEN'S FOOTBATH

The first geological drilling undertaken in Paris (actually under Paris) was carried out by Héricart de Thury in 1814. Dubbed "The Quarrymen's Footbath", the well contains crystal clear groundwater that has percolated into the drilled-depression. The only way to detect its presence is to step into it. One can only guess the mischievous pranks guides carrying candles and torches must have had with their tours. The water was subsequently used by quarry workers to mix cement required for the Catacombs.Limestone is more or less finely porous and permeable to water. At depth - from a few centimeters to several hundred meters - and depending on the series of geological strata and the relief, the rocks are saturated with water. This forms a series of superimposed phreatic zones or aquifers, separated by impermeable argillaceous (clayey) rocks. The water table represents the first phreatic zone to be reached when a well is dug such as the Quarryman's Footbath. Its surface fluctuates with the whim of the rain or even the nearest river. By the way, the principle of artesian wells was demonstrated in 1828 by Héricart de Thury and later applied in the drilling of the Grenelle well in the 15th arrondissement of Paris.

Bains de Pieds des Carrieres, Catacombs Brochure, DAC/Ch. Fouin

THE EMPIRE OF DEATHYou’ve officially entered the Municipal Ossuary having passed beneath the engraved, limestone lintel that declares “Stop! This is the empire of death”. Of course, tens of thousands of visitors every year are hardly dissuaded by the ominous warning. In actuality, this is the “new” entrance, the original being at the end of the ossuary. Visits to the ossuary begin with the most recent bone transfers. The limestone quarries have been closed to the public since 1955, but the Catacombs have remained open. At the time that Guillaumot was strengthening the tunnels beneath Paris, King Louis was closing the overcrowded cemeteries. The exhumations went on for years - long after the King lost his head in the French Revelation in 1793 - until all the bodies had been reinterred in a new realm – this, the Empire of the Dead.

The black tar line on the ceiling was traced as a path to follow by candlelight to prevent 19th century visitors from losing their way in the maze of galleries. An example of how easy it is to get lost is told by the tale of the porter Philibert Aspairta, who entered the quarry alone in 1793 and lost his way. He was found by a survey crew 11 years later and given a proper burial where he had been discovered. In the words of L.F. Hivert in 1860:

“We etched a broad black line commencing at the base of the staircase and meandering all the way through this vast labyrinth. A stray visitor, provided he has light, need only follow this Ariadne’s thread to find the door. From place to place, the line bears an arrow pointing towards the exit door, as the flow of a river is marked on a map.”

Immediately within the entrance to the ossuary is a stele (funerary monument) dated 1810 that commemorates the establishment of the Catacombs. It was moved from the original entrance when the ossuary was expanded.

“Catacombes established by order of Monsieur Thiroux de Crosne, Lt. General of Police, and by Monsieur Guillaumot, Inspector General of Quarries, 1786. Restored and improved by order of Monsieur Frochot, Secretary of State, Chief of the Department of the Seine, by Monsieur Hericart de Thury, Chief Mining Engineer, Inspector General of Quarries, 1810.”

BONE STACKING

In the first years, the Catacombs was a haphazard repository, but renovations in 1810 transformed the underground ossuary into the visible mausoleum (and tourist attraction) that it is today. Skulls and femurs were stacked in repeating patterns in total anonymity, while funerary decorations such as monumental tablets, archways bearing inscriptions, warnings and even poetic verse were installed to complement the walls of bones.

Wikipedia

WALL AFTER WALL LINED WITH BONES

Although some sections of the Ossuary contain a haphazard array of bones, the tour only reveals those neatly arranged in cranium-studded friezes of skulls (maxillae only, no mandibles or teeth!), femurs and tibias. Both macabre and somehow strangely romantic, I could only imagine what fantastic tales of life in Paris the speechless skulls would tell - having lived during reigns of King Louis XV and XVI, the French Revolution, and the Reign of Terror and its infamous guillotine.

The City of Light's 12 million residents live in the world above, while below the streets in the Empire of Death 6 million remain at rest. There are many signs within the Ossuary. Some record the street on the surface above, often with names that since have been changed. Some document the date of consolidation, while others merely record the depth below the surface in both feet and meters. The cemetery of origin from which the bones originated and the date of transfer were carefully recorded. Most of the cemetery-names are long-gone and long-forgotten - with the exception of the most famous and infamous - Saint-Innocents.

“Bones of the Cemetery of the Innocents Deposited on July 2, 1809”

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"Bones of the Church and the Cloister of the White Coats June 22, 1804"

Many of the ceilings (note also above photo) display tiny stalactites as water percolates through the limestone overburden. The incessant dripping over time deposits calcium carbonate in the same manner as seen in karstic limestone caverns.

Tiny stalactites forming on the ceiling of the Catacombs

The ever-present tar-line on the ceiling guides our way. The spiral markings are algal laminations on the floor of the Lutetian Sea, seen from the underside.

Some of the 18th century signage records overlying collapse structures. This one documents the location of a fontis-sinkhole and the initial "J" of quarries inspector Chrétien-Auguste Juncker in 1842.

MEMORIAE MAJORUM - IN MEMORY OF THE ANCESTORS

At the end of the ossuary portion of the Catacombs, that once served as an entrance door, is a low portal with an engraved lintel in Latin - MEMORIAE MAJORUM – “in memory of the ancestors.” The reverse side of the lintel states “Wherever you go, shadowlike death will follow.”

The Catacombs of Paris reminded me of a 17th century Capuchin crypt in Rome beneath the church of Santa Maria della Concezione dei Cappuccini that I had visited years ago. It contains the remains of a mere 3,700 skeletons by Parisian standards that were also transferred and artistically arranged in a similar manner (although many skeletons were clothed and others made into decorative chandeliers). A placard there warns the onlooker in five languages:

“What you are now we used to be; what we are now you will be.”

LA CLOCHE DE FONTIS – THE SUBSIDENCE BELL

The next corridor leads to a gallery consisting of a number of subsidence sinkholes (fontis) consolidated between 1874 and 1875, three of which are over ten meters deep. The rubble that had collapsed from the ceiling has been excavated and allows the viewer to observe its bell-shaped structure.

Rather than cover the walls with hand-stacked masonry-retainers, some subsidence structures were simply consolidated with sprayed cement. The fontis seen below was reinforced with an arch, whereas others were reinforced with an internal shell of masonry. The stratigraphic layers can be viewed in cross section as if seen from within a bell. The colored lines were added to help delineate the strata – an embellishment that I could do without. In all, it’s a quite remarkable catastrophic collapse-structure that can be viewed from within and an incredible display of quarry history. One must remember that these very subsidence bells threaten the lives of Parisians on the surface, although most everyone goes about their daily lives with total nonchalance.

Cloche de fontis aux Catacombes

Many, if not most, of the "bell-holes" are located beneath critical structures on the surface such as buildings, busy street and Metro stations. The apex of this fontis contains the date "1875" written in mirror-image.

TECTONICS, GEOLOGY AND PALEONTOLOGY ON DISPLAY

At three various locations within the Catacombs, the story of the tectonic and geological evolution of the Paris Basin and the Lutetian Sea is beautifully displayed on murals in understandable terms. During the Lutetian epoch of the Eocene, centered about 45 million years ago, the waters of the nascent Atlantic Ocean repeatedly flooded the continental shelf of Europe and its many basins. The Anglo-Paris Basin received sediments of sand, clay and limestone.

One such layer, a limey sludge, hardened with the passage of time until it became the fine, even limestone known as Banc de Saint-Leu, which is highly sought after for cutting into building stone. And within the epicontinental basin, a shallow, sub-tropical sea much like the present-day southern Mediterranean was teeming with marine life - worms, gastropods, bivalves, corals, urchins, fish, nautiloids, crabs, sharks, etc.

Plaster cast of Campanile giganteum, an exceptionally large marine gastropod from the Eocene epoch of the Paris Basin, was on display within the Catacombs

Nummulites laevigatus,a foraminifera that left a fossilized shell that looked like a "liard" (a small Medieval coin) formed a meter-thick layer called pierre a liards or liard stones.

FAMOUS NATURALISTS OF THE LUTETIAN

By the end of the lower Lutetian, the sea had reached the site of present-day Paris. With its final recession, the lagoonal and mangrove landscape gave way to an arboreal savanna rich with a terrestrial flora and fauna. The skeletons of extinct early mammals - such as the pre-ice age mammal Palaeotherium - were excavated from the gypsum mines of Montmartre on the Right Bank and studied by the French naturalist Baron Georges Cuvier, founder of the science of comparative anatomy and vertebrate paleontology. Cuvier was not ready to suggest that animals had evolved through time, but he did arrive at the inescapable conclusion that the fossils were the remains of animals long-extinct, implying that God had allowed some of his creations to vanish.

This commemorative plaque is on the wall of Louise-Michel square at the northern end of the rue Ronsard, which was the entrance to the quarries of Montmartre that are beneath the Basilica of Sacré Coeur. It was here that Cuvier discovered mammalian fossils in 1798.

Cuvier also noticed that the Lutetian fossils of the Paris Basin differed with each strata. Working with the mollusk expert Alexandre Brongniart, Cuvier was able to identify the basin's different layers based on their distinctive fossils.

Cuvier's and Brongniart's joint venture in delineating the stratigraphy of Paris in 1832

Cuvier avoided conflict with the powerful theologians of his time in his interpretation that the extinct animals were victims of Noah's biblical flood, and in so doing, became an early proponent of catastrophism in geology (past dramatic events can explain changes in geological features and the extinction of species). The two established the first geologic maps and cross-sections in France and Continental Europe including the Paris Basin.

This 1810 copperplate, colored geologic map of the environs of Paris (arrow) by Cuvier and Brongniart was established in part by identifying fossils in various sedimentary strata. Limestone is pink; gypsum is blue; marine marls are yellow; green areas are freshwater terrain. William Smith's many geologic maps of England were also being generated by this time.

EXITING THE CATACOMBS

One must depart from the Catacombs in the same manner as the arrival by ascending a narrow, spiral staircase - this time with only 83 steps - from a depth of 54 feet from the street. Unlike the entrance staircase, the exit dates back to the origins of the Catacombs. The exit is at 36 Rue Rémy-Dumoncel, still within the working-class suburb of Petit-Montrouge.

We have completed a subterranean journey of 1,500 meters, of which 600 meters proceeded between the walls of bones of the Ossuary. In spite of the distance, which seemed longer due to the narrow tunnels and absence of a visual horizon, we only experienced a very small section of the Catacombs and a tiny section of the underground limestone quarries that lie beneath the Left Bank!

As if 6 million skeletons wasn't enough, a subtle reminder of the tenuous grip on life that we all possess rests strategically on the wall immediately at the top of the arduous stair-climb to the street.

Our unceremonious, eye-squinting exit from the Catacombs was from an unmarked, nondescript stone-structure on a quiet side street of Petit-Montrouge. Across the street (to the left outside the image) is a fantastic bookstore with numerous titles on the quarries and the Catacombs, however, most were written only in French.

A REMARKABLE TRANSITION FROM CEMETERY TO PUBLIC SQUAREIt's been over 225 years since the King's edict to close the Cemetery of Saint-Innocents was issued. Since then, much of Paris's landscape has changed, most notably during the radical urbanization program of Napoléon III and his Prefect of the Seine Georges Eugene Haussmann in the 19th century. The limestone quarries and the overcrowded, center-city cemeteries have closed, and their bones have been moved to the Municipal Ossuaries called the Catacombs.

There’s little on the modern landscape of Paris to remind us of the intolerable conditions that existed at Saint-Innocents during the 18th century, that is, unless you know where to look. Following the closure of the Cemetery of Saint Innocents in 1786, the Church of Saint Innocents was destroyed as the bodies were being transferred in the night to their haven of peace within the Catacombs. The Fountain of the Nymphs, which had been erected against the wall of the church in 1549 and was also scheduled for destruction, was dismantled and rebuilt in the center of the new square and marketplace, Place Joachim de Bellay. A painting by Hoffbauer in 1850 depicted the transformation of the cemetery into a bustling marketplace with stalls and umbrellas.

The square and market of Place Joachim de Bellay with the Fountain of Innocents in 1850Theodor Josef Hubert Hoffbauer (1839-1922), Public Domain.

Today, after several embellishments that included a larger pedestal and central fountain with a series of cascading basins , the newly-titled Fountain of the Innocents is within the square but located in a small corner of the original cemetery. The proximity of the Saint-Innocents Cemetery to the original marketplace of Les Halles is preserved in the square’s proximity to the Forum des Halles, a modern underground market and shopping area reconstructed in 1971 from the original market.

Modified from Wikipedia

A portion of the original, bone-containing charnel house still stands along the border of the square and houses a popular pizza joint. The square is a quiet and peaceful place with Parisians reading and kids playing ball. What indescribable sights the monument has seen!

Today, quarry inspections are still conducted by the Inspection des Carrieres, established in 1777. This 20th century manhole cover on the Left Bank testifies that the IDC is still on the job. The techniques of quarry reinforcement have changed. They are no longer consolidated with masonry work but by drilling and injecting backfill materials.

Ironically, the savior of the city - Charles Axel Guillaumot - never had a street, monument or plaza named after him. What’s more, his remains anonymously joined the millions of bones and skulls in the Catacombs, the ossuary repository that he had created to clean up the cemetery of the Saint Innocents. Another point of interest, Guillaumot was imprisoned in 1791 during the French Revolution and removed from his position because of his appointment by the King. Recognizing his importance to the city, he escaped the guillotine and was returned to his position in 1795.

As for the River Bièvre, the tributary along which Romans exploited its banks for limestone, it flows freely in the outskirts of Paris and still empties into the Seine but is now almost totally submerged and diverted within vaults and tunnels under the buildings and streets of the Left Bank. The Bièvre was heavily polluted by chemicals from the tanneries that lined it in the 19th century. Local residents have called for the rehabilitation and unearthing of the Bièvre or at least a portion of it on the grounds of the Muséum d'Histoire Naturelle.

A "freely-flowing" Bievre River in the 5th arrondissement c. 1862 taken by the government commissioned photographer Charles Marville Wikipedia and the Museum of Art, The Horace W. Goldsmith Foundation Fund

These days, in addition to becoming a city-promoted tourist attraction, the Catacombs have also become a parallel, sub-universe populated by "cataphiles" - illegal subterranean explorers and young, bohemian Parisians who use the underground galleries and tunnels as party venues and places to hang out and paint decorative murals. Secret entrances exist throughout the Left Bank of Paris via sewers, the Metro and manhole covers.

From National Geographic

In spite of sophisticated mapping, detailed inspections and modern quarry consolidations, catastrophic collapses still occur on the Left Bank as seen below recently. Notice the Lutetian stratigraphy within the fontis! On average, seven collapses occur a year in Paris, in spite of intensive efforts to stabilize the underground quarries. A collapse in 1966, triggered by heavy rains, opened a chasm in the street that swallowed six streets and part of a soccer stadium. Twenty-one people were killed, 273 were left roofless and 23 buildings were completely destroyed. In 2003, an entire school building collapsed into Metro tunnels compromised by underground excavations. Anxious eyes continue to watch the streets and people of Paris.

Early warning of collapse is possible with remote Interferometric Synthetic Aperature Radar (InSAR) emitted from satellites and aircraft. The process can spatially monitor small, slow-rate vertical ground deformations seen with subsidence, uplift, landslides, volcanoes and earthquakes and generate maps of surface deformation. InSAR has been used successfully in major cities such as Paris, and has become a valuable tool for land-use planning and natural as well as anthropogenic risk assessment.

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Mean Amplitude Image of Paris with Satellite Radar Interferometry Analysis Arrow “a” indicates a mean subsidence event of -3mm/yr in the Grand Palais area during the period 1992-2000. Arrow “b” corresponds to the Saint-Lazare area studied in 2000 and 2002. Arrow “c” corresponds to a subsidence of -2mm/yr around the Montmartre area.Modified from earth.esa.int/psic4/background.html

Color-coded maps of surface deformation can be generated over time.

Set of Phase Screens of ParisThe various colors represent levels of deformation.From asprs.org

IN CONCLUSION

My recent visit to Paris served to further reinforce the theme stated in the masthead of my blog that “Geology is all around us, scarcely thought of as we go about our lives. Yet, it affects everything we do as a civilization, as a society and as individuals.”

The Lutetian deposits of gypsum on Paris’s Right Bank beneath the hills of Montmartre and Belleville provided plaster of Paris for the city and the world. The Left Bank deposits of limestone built the city, and the quarries that honeycombed its depths provided a necropolis for the countless millions of Parisians buried there.

ADDENDUM

Upon our ascent from the Catacombs, my wife and I found ourselves within a stylishly quaint neighborhood of Petit-Montrouge. What a contrast from where we had been amongst the Empire of the Dead and into the Realm of the Living. In a matter of minutes we had traveled from pre-17th century quarries through an 18th century ossuary, into a 19th century fontis excavation, up a set of 19th century steps, and out of a 20th century building to the 21st century. I took out my Smartphone, launched the App for Zagats and found a perfect bistro for lunch for the two of us just down the boulevard. La joie de vivre!

VERY INFORMED PRINTED SOURCES OF INFORMATION AVAILABLE FROM THE CATACOMBS BOOKSTORE AND ON-LINEAtlas du Paris Souterrain under the direction of Alain Clement and Gilles Thomas, 2001. A fantastic, thorough and entertaining presentation in French with wonderful photographs.Paris Souterrain by Emmanuel Gaffard, 2007. The Catacombs of Paris by Gilles Thomas, 2011. Another thorough presentation.

Oscar, Thanks so much for your generous comment! I really enjoyed writing it! On my recent trip to Paris with my wife, I had no idea that I was heading on an urban geological field trip that would be so enlightening. Great company. Great food. Fabulous artwork. A beautiful city. And geology. What more could I ask for?

Hollis, Thanks for visiting and the comment! This recent visit was an eye-opener for me. I've been to Paris a few times but never really understood the connections of history, politics and art. I find it quite interesting and ironic that it was geology that facilitated my enlightenment.

I've just finished reading the novel Pure by Andrew Miller (2011), a prize-winning fictionalized story about the closure of le Cimetière des Innocents. Curiously, I started scrolling through the web: thanks for this entry!!

I stumbled over your post while researching about the history of the Catacombs, since I am working on my own post on this subject. Your way of telling combined with images and pictures is suberb. Thanks so much.

I apologize if this comments appears twice. I'm not sure the first one went through.

What a great and informative post. Paris' underground is quite an amazing place. I used to live Paris, but knew very little about the complexity of its "basement".

I have a quick question to ask you if you don't mind. I'm currently writing a story that takes place in the Catacombs. I'm especially interested in the "Bains de Pieds des Carrieres". Do you recall by chance how they prevent visitors from getting too close to the well? I visited the Catacombs years ago, but I cannot remember if the access is closed by a gate or is simply not accessible through the path taken by visitors.

Any help would be appreciated. I wish I could go check for myself, but I no longer live in France and hope to find someone who can help me with this detail.

Greetings Julien, Thanks for the kind words about my blog! A corridor that one follows through the Catacombs, within the section that is open to the public, passes by the steps that lead down to le bain. You can not just walk down to it. Specifically speaking, I seem to recall a chain preventing one's entry down the steps. I could be mistaken, but I distinctly recall wanting to descend to get more photographs and being prevented from doing so.

Thank you so much for your feedback. That's perfect. I knew there was some kind of measure taken to prevent people for going down the steps, but I couldn't find exactly what was put in place to do so. Thank you again for your prompt answer and keep digging – although I'm not sure you do much of the digging yourself ;) !

Great geology posts, I only just found them. It turns out (and I only just learned this myself) that a "fermier" in the past was a tax collector, not a farmer (they evolved into farmers later). See for example https://en.wikipedia.org/wiki/Ferme_générale which mentions the wall.

Some Stuff About Me

I was the kid in the lyrics of the Jackson Browne song “in ’65 I was seventeen”, when my educational efforts were directed toward a degree in biology and a career in a health profession. Many years later, the marine fossils I found growing up in Central New York State led me to paleontology, the evolution of vertebrates and to developmental biology. It wasn’t long before I came to appreciate the importance of an education grounded in geology and tectonics. Former life and former landscapes are indeed inseparable. In this blog I offer a descriptive, interpretive and photographic perspective of our world, both past and present, and both within my New England home and well beyond.

The moss-covered travertine dome of Ribbon Falls, Grand Canyon, AZ

Peek-A- Boo Gulch Slot Canyon in the Escalante Canyons district of the Grand Staircase, UT

Cinder Cone volcano Pu'u ka Pele on the flanks of shield volcano Mauna Kea on the Island of Hawaii

View of the La Sal Mountains through Mesa Arch carved into the Navajo Sandstone in Canyonlands

Park Avenue in Arches National Park are what's left of a vast mesa of the Entrata Sandstone erg

Navajo Sandstone at Head of the Rocks Overlook in the Escalante Canyons district of Utah

Disclosure

This blog is not affiliated or associated with any individual, group, business or institution. There is no financial compensation or exchange for services whatsoever derived from it. My photos that have appeared in journals, magazines, books, teaching guides and museums were donated free of charge. It is my hope that it will create a forum for the exchange of ideas and provide my readers with engaging, useful, educational and relevant information about the world we live in and the ones that came before it. All photographs on this blog are taken by me unless otherwise noted.

Me in 2005 and 2017

Some Comments From "Written In Stone...seen through my lens"

Here are a few of the favorable comments that I’ve received on Written In Stone…seen through my lens. Thank you all for the positive feedback! Doctor Jack

"You are one of the best geo-bloggers I know of. Your posts are thorough and comprehensive. Truly gems of writing and geo-explanation. Can't wait to see what you come up with next!" By Wayne Ranney

"Intimidatingly thorough and well done for someone who's not a career paleontologist! The delivery of the subject, fully within context, should serve as an example to all those within scientific communication." By British paleontologist Dave Marshall

“Your blog Written in Stone is now homework for the weekend for my master’s and undergrads at Keene State. Both classes learning about “Big Picture” environmental studies and how geology serves to underpin our research interests in so many ways. Keep it going! LOVE!” By Peggy

“To Dr. Jack Share, whose geological knowledge, reference and enthusiasm have been most valuable and inspiring.” By Geocaching.com

"What an incredible blog to share. As a river guide in Grand Canyon for over 20 years I have never seen the Great Unconformity explained so well. You have a magic to your words and photos. Thank You Jack!" By Walter Mackay of Colorado River and Trail Expeditions (CRATE)

“Another beautifully done post from Dr. Jack Share, who does geoblogging the way it should be done. In fact, anyone who cares about web design could learn from his blog.” By Scooped by YEC Geo

“Fabulous photographs! It's the view a geologist on the ground wants but rarely glimpses. Thank you so much for the big picture and so many great examples of textbook structures.” By Sharon

"Earlier this year, I discovered a superb geological and photographic blog that I had not encountered before by Jack Share." By Michael Welland, British geologist and author of "Sand: The Never-Ending Story"

“Simply astounding. Thank you for this post!” By Geoflier

“Finally, Jack Share of Written in Stone … seen through my lens writes an epic post about the Great Unconformity in the Grand Canyon. He includes tons of photos and this is only part 1. Wonderful stuff.” Brian Romans from Clastic Detritus of the online Wired Science Blog Network

“I've never been to Shiprock, but I've seen pictures. However your photos and your ability at focusing on just the right angles and subjects far surpasses what I've seen before even with Arizona Highways. Thanks so much for these. I've had to scroll up and down a number of times to take it all in.” By Timeless

“Wow! You’ve really laid out a comprehensive and well-organized lesson on arguably the most treasured resource in our field of geology. Your photos are incredible as well, especially the aerial shots! Thanks for putting this together. I just stumbled onto it at work, and I'm going right back when I get home to check out more. Thanks for an awesome post!” By Mike

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"I just discovered your wonderful website about the Paris underground. Your photos are quite beautiful. Congratulations for the amount of information present, even the face of Guillamont. I'm going to send your website address to his family of 800 people." Gilles Thomas, author of "The Atlas of Underground Paris."

"I have to say that this is one of the best laid out and informative blogs I have seen in a long time. I have seen several that post pictures of the rocks and their formations, but not one that explains it all. So well done to you. Great Blog." By Spiral Staircase